The plaintiffs won’t have to prove the things you list. All they will have to prove is that MB didn’t call the cops as soon as they knew there was a shooting at their property.
The emotions of the jury will do the rest.
You can take that to the bank.
The Mandalay Bay portion of the lawsuit is probably fifty-fifty.
The bump-fire stock manufacturer portion is DOA. They can’t be held liable for the illegal use of what amounts to a novelty product.
The festival promoter? That’s got teeth. One can easily argue that when putting on an event such as that, it is the promoter’s responsibility to ensure that in the event of an emergency - yes even one that has “never happened” - their staff are all adequately trained on what actions they should and shouldn’t take. They should be trained on where the emergency exits are and how to get people to them; whether or not to turn on the lights; whether or not to get on the mic and give directions...etc. And there should be medical personnel on site as well. None of that is saying it would have made any difference - but if the plaintiff can show they didn’t have these things...it may make a difference.
And I was a musician in a former life so I’m well aware that 90% of the staff at these shows are either close to or as baked/intoxicated as the rest of the crowd. That could work against them as well if it comes out in depositions.
>>The emotions of the jury will do the rest.
You can take that to the bank.<<
Assuming it survives the inevitable motion to dismiss.
I doubt it will as a matter of law.